1990 740 Turbo Wagen

Well we have had the car a little over a week and it seems to me that the fuel economy is low, in less than 100 miles I have burned through 1/2 of fuel (roughly 12mpg).

I checked the O2 sensor and it flucuates from .2~.8 volts I am assuming it is good based on previous experiences.

Found no vacuum leaks using MAP gas, so the intake tract is in good shape.

No play in the Turbo shaft.

I did try the breakout box on the strut tower and the one time it worked it blinked 1-2-1 indicating the AMM. That could be a false indicator because prior to that I disconnected the AMM while the car was running and the car stumbled and ran rough, then when I connected it all was fine again.

What else could I be looking for, I read on turbobricks that a pre-pump on these cars can cause a consumption issue. Is that true?

Also one more question, I noticed that on the intake side of the engine in the area of knock sensor there is another 2 pin connector wire that is just there. Knock sensor is connected and the cold start is connected, I can't see what this should be attached to any ideas? If I get time tonight (preparing to leave for Colorado in the morning) I will post some pictures of the connector in question.

TIA for the help

Brian